Common terminology and definitions about HVAC Plenum Access Doors, AHU Wall Panels, and Viewport products.

Apex: The highest point, at the top, the culmination.

Astragal: Flat vertical trim molding attached to one twin door leaf that other door leaf closes against.

Galvannealed: Sheet steel that is heat treated after coating to produce a zinc-iron alloy and eliminated the spangle. Can be painted without further surface preparation except for normal cleaning.

Density: How tightly compacted a material is, ratio of mass of an object to its volume. Typically expressed in pounds and the high the number the more rigid.

Door Frames: Mounting frame and door panel frame are 6063-T5 extruded aluminum.

Door Size: Measured from outer most part of mounting frame, excluding mounting Flange, (part of frame that slides into the wall) sized 1/4″ under wall opening.
Embossed Aluminum: Aluminum sheet metal with a stucco pattern and a rough finish on both sides.

Galvanized: Zinc coating on cold rolled sheet steel, applied through a “hot dipped” process that produces a spangle pattern or an “electrolytic process producing light gray finish without spangle.

Hinge Location: Door swing is reference by (L/H) left hand or (R/H) right hand which is the location of the hinge when viewing either an in-swing or out-swing door from the exterior side.

In Opening or In-swing: Door opens into positive pressure “Blow Through” plenum. P = Positive.

‘K’ Factor: A rate at which heat flows through material, the lower the number the better the insulation value. The thickness of insulation divided by ‘K’ = the ‘R’ factor.

Out Opening or Out-swing: Door opens out to exterior on negative pressure “Draw Through” plenum.

N: Negative.

PA: Plenum Access.

‘R’ Factor: A measure of the resistance of heat flow. As the thickness of an insulation increases the ‘R’ factor increases, the higher the better the insulation value.

Removable Mullion: Vertical frame member that divides the twin door mounting frame in half and provides a gasket seal for the two door leaves to latch and seal against. The mullion is removable to allow full access through the door opening.

Spangle: Bright sparkle finish with snowflake-like pattern that gliders, is present on Hot Dipped Galvanized sheet steel.

Twin Door: Two independent door leaves hinged along the left and right jambs in one common mounting frame.